The present invention pertains generally to sound barriers and is more specifically directed to an improved sound barrier construction for out-of-doors use, such as a highway noise barrier.
It is believed generally fair to say that highway noise is recognized as a significant environmental problem. The problem is most noticeable in the more congested areas where high-speed expressways or freeways pass through residential areas. Where a highway is depressed below ground level, the problem is less severe because of the adjacent embankments provided by the depressed construction. Where the highway is at or above ground level, the problem is more severe. In either case, the effect of highway noise can pose a serious environmental problem, particularly in residential areas.
In attempts to solve this problem, various construction techniques have heretofore been employed. For example, natural land berms are often utilized to provide a physical barrier between the highway and adjacent properties to deflect the noise from the traffic on the highway. While such natural berms may be aesthetically and environmentally pleasing, they do require heavy earth moving equipment for their construction, and they may also require additional construction work for drainage and other similar considerations. Also the berms may be covered with vegetation, such as grass or plants, which may require maintenance at relatively frequent periodic intervals. A further problem with a natural berm is that it occupies a rather substantial land area in order to achieve the necessary height which is required to be effective as a sound barrier; in other words, the higher the berm, the wider its base, and naturally a larger amount of fill is required to form the berm.
In attempts to provide alternate solutions for this problem, concrete sound barriers have also been developed and utilized as an alternative to natural berms. Such "concrete berms" do possess the advantage of requiring considerably less land area than natural berms; however, they possess a number of serious disadvantages. The use of concrete, due to its massive weight, dictates the necessity of very substantial and deep foundations and footings. Furthermore, such concrete berms typically require vertical posts which are embedded deeply in the earth and which project upwardly for essentially the full height of the barrier. Concrete wall sections between the vertical posts are typically pre-cast and installed between the posts to complete the installation. Because concrete berms may typically be employed where there are space limitations between the highway and the adjacent property, they can pose a safety hazard to highway traffic, should a vehicle, for whatever reason, leave the highway and collide with the concrete barrier. Thus, it is believed that concrete sound barrier berms do not provide a satisfactory solution to the reduction of highway noise along adjacent property.
The present invention is directed to a new and improved sound barrier system which affords a number of significant advantages and benefits over prior types of sound barriers and berms. Like the concrete barrier, the sound barrier of the present invention has the advantage of being suitable for installations where only limited space is available, yet it does not pose nearly the safety hazard to highway traffic that a concrete berm poses. The sound barrier of the present invention is more economical from the standpoint of more efficient use of lighter weight materials, and relative ease of erection. This means that heavy equipment and substantial foundation work are not required for installation of the sound barrier of the present invention. Indeed, at most, it may require light power equipment which can excavate a comparatively shallow trench, and the actual assembly and erection of the sound barrier of the present invention can be conducted by workmen using conventional hand tools, manual and/or power. The preferred embodiments of the present invention disclosed herein employ stress-skin panels each comprising a wood framework whose opposite sides are faced with plywood sheets. In one preferred embodiment, all panels are of the stress-skin type while in another, stress-skin panels alternate with plywood sheets. Immediately adjacent panels are in abutment along vertical joints and an earth anchor, embedded in the earth, is secured to the bottom portion of each joint. In the preferred embodiments, the included angle between immediately adjacent panels is obtuse, which promotes efficiency in the use of material along the overall length of the barrier in conjunction with good vertical stability and other attributes of the invention. The arrangement provides a material-efficient, light-weight, yet rigid, construction which is devoid of substantial vertical structural support members embedded in and projecting above the ground, such as the concrete posts of a concrete barrier. The barrier of the present invention can successfully withstand the environmental activity to which it is subjected, even high winds, yet in the event of being struck by an errant vehicle, it would not pose the safety hazard to vehicle occupants which a concrete barrier would pose. It is also less dependent on soil conditions than concrete barriers.
A further advantage is that the invention, in its preferred form, possesses the benefits of prefabricated construction for most all its component parts, yet at the same time it is versatile enough that a variety of embodiments may be constructed by relatively minor modifications to the prefabricated parts, as individual installation sites dictate.
The foregoing features, advantages and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings wherein like reference numerals designate like parts. The drawings disclose presently preferred embodiments of the invention in accordance with the best mode presently contemplated for carrying out the invention.